138 



HOROLOGY. 



of vibrations in a second, while others gave only one. 



pj is num i, er gigfo ma j e one v ib,. at j on ; a second, and 

 was the one which gave the best performance of all 

 those that he had constructed. It seems to have been 

 considered as a wonderful discovery, that jewelled holes 

 wore down the pivots, and thickened the oil, after 

 they had been used for upwards of a hundred years. 

 How came this not to be sooner observed, when so 

 many were engaged in making chronometers, and that 

 too in considerable numbers ? That pivots, from a 

 length of time, even with good oil, and with greater 

 probability from bad oil, may have got, as it were, 

 glued in their holes, there is little reason to doubt ; 

 but this never arose from particles wearing away from 

 either the steel or the stone, by the friction of the 

 pivot. Let any one try to whet a graver, which re- 

 quires some degree of force, on a polished Scotch pebble, 

 for instance, and they will find that no exertion what- 

 ever will make the graver bite the stone, or the stone 

 the graver : for where any effect of this kind takes 

 place, it must be nearly mutual. The hardness of the 

 Scots pebble is well known to be much inferior to that 

 of the ruby or sapphire. After being exposed to the 

 sir for a considerable time, oil gets viscid and thick, 

 which arises, as has been observed by chemists, from 

 its absorbing or attracting oxygen. We suspect that 

 oil, from this cause alone, may become more glutinous 

 at a jewelled hole than at a brass one. By its applica- 

 tion to brass it soon acquires a bluish green tinge, as 

 if something acted upon it. This is owing to the metal 

 becoming oxidated by the joint action of the oil and air. 

 The oxide thus formed combines with the oil, and forms 

 a metallic soap, which is much less tenacious than that 

 formed at a jewelled hole. By the continuation of this 

 process, the hole in brass in time becomes wider, and 

 the oil disappears, leaving the pivot and hole in a great- 

 er or less degree wasted ; and instead of the oil we have 

 the metallic soap, which has hitherto been cansidered 

 as rust. To be convinced, however, that this is not the 

 case, we need only attempt to wipe it off from the pivot, 

 from which it easily parts, and which it would not do 

 were it really rust. Oil, however, can have no action 

 on the jewelled hole, and any change that is effected by 

 the oil must be confined to the steel pivot, on which its 

 action is so exceedingly slow, that a great length of 

 time must elapse before the oil is decomposed and dis- 

 appears ; and hence what has been called rust in a brass 

 hole, is seldom or never met with in a jewelled hole. If 

 a little fine Florence oil is put into a small phial for 

 about two-tenths of an inch deep, and remain for a few 

 years, it will become exceedingly viscid and glutinous, 

 and will be intermixed with parts tinged with red of 

 various shades. The same appearance is sometimes seen 

 at jewelled pivot holes, and has been erroneously sup- 

 posed to be produced by the operation of the pivot on 

 the hole. It is singular that oil will act more forcibly 

 on fine brass than on the common sort, or even on cop- 

 per ; a metallic soap somewhat resembling verdigrease 

 will soon show itself on the former, while the Latter will 

 hare no appearance of being injured. But we are not 

 to infer from this, that copper holes would be preferable 

 to those made in fine brass ; for although the oil in this 

 case would be more durable, from its acting more slowly 

 on copper than on brass, yet the increase of friction from 

 the copper would more than counterbalance this advan- 

 tage. It can hardly have escaped the eye even of the 

 most indifferent observer, that oil acts more readily and 

 forcibly on new than on old work. On the former, it will 

 frequently showitself inthecourse of 24 hours. Oil varies 



so much in its quality, that some will become so thick and Jewelling of 

 viscid in the course of a few months, as to stop the ma- \ 

 chine altogether. This has occurred in the experience of """V" 

 a very celebrated artist, who informs us that " his regu- 

 lator, which has been found to go to a greater degree of 

 accuracy (though not to a second in two months, as has 

 been said of others) than even that at Verona, as observed 

 by the astronomer Cagnoli, or that at Manheim, as ob- 

 served by Mayer, was found to perform very indiffe- 

 rently after being cleaned, and at the end of three or 

 four months stopped altogether, which arose from the 

 application of bad oil." We arc of opinion, that where 

 the pivots are small, and the revolutions of the wheels 

 quick, jewelled pivot holes are the best. It will not 

 be an easy matter to do without oil, particularly 

 in pocket or box chronometers, although astronomical 

 clocks or regulators may be so constructed as not to re- 

 quire it. 



CHAP. V. 



On the Machinery for going in time of Winding. 



THE earliest machinery for going in time of winding, 

 is the simplest and best that has yet been produced, al- 

 though, upon the whole, it may not be so convenient 

 in its application. In the old thirty hour clocks, the 

 first wheel of the going part had on its arbor a fixed 

 jagged pulley A : (See Plate CCCIV. Fig. 6.) On the 

 arbor of the first wheel of the striking part was a move- 

 able jagged pulley II, with click and ratchet to it. Over 

 these, and through or under the pullies of the counter 

 weight/) and main weight P, went an endless cord, woven 

 either of silk or cotton. Both parts of the clock were car- 

 ried on by a single or main weight; and, when winding 

 it up, this was done by the striking pulley; by which 

 means, the weight acted constantly on the going part. 

 This is a method which we adopted in some common 

 regulators, and afterwards found it was the same that 

 Berthotid had used in some of his. The moveable and 

 winding up pulley with its ratchet was on a fixed stud, 

 having a click and spring, which were fixed to one of 

 the plates, as was also the stud. The other pulley was 

 on the arbor of the first wheel, and fixed to it. The 

 only inconvenience and objection to this contrivance, 

 particularly in eight day clocks, arises from the wear- 

 ing of the cord on the jagged part of the pullies, which 

 produces a great deal of dust, and makes the clock get 

 sooner dirty than it would do, if this was effected in a dif- 

 ferent way. In clocks which go a month, or six months, 

 as some of Berthoud's did, this will be very much obvia- 

 ted, particularly with a fine and well wove silken cord. 



There is a very ancient way of going while winding, 

 which was long applied to the fusees in clocks and watch- 

 es. On the inside of the great wheel is another wheel, 

 whose teeth are cut to look inward to the centre, upon 

 which acts a pinion of six, which runs in the bottom 

 of the fusee, and is turned round with it. The fusee 

 arbor is free within both the great wheel and the fusee ; 

 upon it is fixed the fusee ratchet, and a wheel with about 

 half the number of teeth of those in the inward toothed 

 wheel. It is evident, that if the fusee arbor is turned 

 round, the wheel fixed on it, which acts also into the 

 pinion of six, will by this make the pinion turn ; and 

 this again, acting on the inside wheel teeth, will apply 

 as much force to it, as the fusee requires in setting up. 

 When wound up, the click in the great wheel, as in 

 the ordinary way, stops the fusee by the ratchet from 

 5 



Machinery 

 for going in 

 time of 

 winding. 



First mecha- 

 nism for this 

 purpose. 



1-LATE 



CCCIV. 

 Fig. 6. 



Another 

 mechanism 

 forgoing in 

 time of 

 winding. 



